A detention officer witnessed Day and another inmate, both assigned to Unit 7D, begin arguing with one another May 10, an arrest warrant affidavit states.

As the two argued, Day rushed the other inmate and tackled him into a desk, authorities said. Day then picked up the man over his head and “forcibly slammed the victim onto a concrete floor,” the affidavit states.

Response officers responded to the unit and found the man on the floor, while placing Day into restraints.

Medical staff transported the man to the medical section, where they determined he needed further medical treatment and sent him to University Hospital.

Day admitted to slamming the inmate onto the floor during an interview with a sergeant, the affidavit states.

On May 13, doctors at University Hospital told detectives the injured inmate had severe trauma to his head that resulted in his brain swelling. A large portion of the inmates skull was removed to ease swelling, adding that he had various bone fractures and a collapsed left lung.

Day was still behind bars Sunday evening. It wasn’t immediately known what charge had originally landed Day in jail